import tensorflow as tf
w1=tf.Variable(tf.random_normal([2,3],1))
w2=tf.Variable(tf.random_normal([3,1],1))

x=tf.placeholder(tf.float32,(1,2),'input')
a=tf.matmul(x,w1)
y=tf.matmul(a,w2)
sess=tf.Session()
sess.run(tf.initialize_all_variables())
print(sess.run(y,feed_dict={x:[[0.7,0.9]]}))